Match List - I with List - II.
| List - I | List - II | ||
| (Components of Reactor) | (Function) | ||
| (A) | Uranium | (I) | Reaction rate can be controlled by it |
| (B) | Moderator | (II) | Slows down the fast moving neutrons |
| (C) | Control rod | (III) | Used for fission reaction |
| (D) | Coolant | (IV) | Transfers heat from core to turbine |
Choose the correct answer from the options given below :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) - (III), (B) - (II), (C) - (I), (D) - (IV)
A nuclear reactor runs a controlled chain reaction: the fuel undergoes fission, slow neutrons keep the chain going, the number of neutrons is kept in check, and the heat produced is carried away to make steam.
(A) Uranium — this matches (III) Used for fission reaction. Uranium (\( {}^{235}_{92}\mathrm{U} \)) is the fuel; its nuclei split when they absorb slow neutrons.
(B) Moderator — this matches (II) Slows down the fast moving neutrons. Fission neutrons are fast; light nuclei such as those of heavy water or graphite slow them down by collisions, because slow neutrons are far more likely to cause fission of \( {}^{235}\mathrm{U} \).
(C) Control rod — this matches (I) Reaction rate can be controlled by it. Rods of cadmium or boron absorb neutrons; pushing them in or pulling them out changes the number of neutrons available, and so the rate of reaction.
(D) Coolant — this matches (IV) Transfers heat from core to turbine. The coolant (water, for example) carries the heat from the core to the steam generator that drives the turbine.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Nuclear Reactor – “… Therefore, in reactors, light nuclei called moderators are provided along with the fissionable nuclei for slowing down fast neutrons.”
Nuclear Reactor – “… The reaction rate is controlled through control-rods made out of neutron-absorbing material such as cadmium.”
Nuclear Reactor – “… In such a reactor, water is used both as the moderator and as the heat transfer medium. … In the steam generator, evaporation provides high-pressure steam to operate the turbine that drives the electric generator.”